The invention is based on a measuring device for contactless detection of a rotational angle. From German Published, Unexamined Patent Application DE-OS 196 34 381.3, published later, a sensor is known that is disposed in three planes one above the other. The rotor forms the middle plane and comprises the carrier plate for a permanent magnet. The carrier plate is of magnetically nonconductive material, so that the magnetic flux proceeds via the other two planes, that is, the stator, and is controlled with the aid of two spacers that are disposed between the two planes of the stator. Although a relatively wide angular range can be measured without a change of sign with this sensor, nevertheless because of the construction in three parallel planes, it is relatively large in the axial direction.
It is therefore an object of the present invention to provide a measuring device for contactless detection of a rotational angle which avoids the disadvantages of the prior art.
In keeping with these objects, one feature of present invention resides in a measuring device in which the rotor and the segments of the stator are formed in a disk-shaped manner, the rotor is composed of magnetically conductive material, and at least one short-circuit piece is disposed on one of the segments of the stator.
The measuring device for contactless detection of a rotational angle according to the invention, has the advantage over the prior art that the sensor has a relatively small size in the axial direction. It is constructed in only two planes. The carrier plate of the permanent magnet, which represents the rotor, acts at the same time to guide the magnetic flux. Furthermore, this construction reduces the number of parts and the attendant expense and effort of assembly.
By a protrusion of the short-circuit piece past the carrier plate, or of the carrier plate past the short-circuit piece, insensitivity to an axial play and/or a radial play of the sensor is attainable.
Because of its simple construction, the sensor can be integrated with relatively little effort or expense of assembly in various systems, such as a throttle measuring device, a pedal module for a transducer for the accelerator pedal value, or can be used as an independent sensor in throttle valve transducers or in a vehicle suspension system.
The novel features which are considered as characteristic for the present invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.